Auto merge of #7162 - yaahallo:clippyargs, r=ehuss

reimplement arg passthrough for clippy-driver

Prior to this change, the old cargo subcommand version of `cargo clippy`
had a feature to pass trailing args down to clippy-driver but when this
the subcommand was reimplemented inside of cargo this feature was left
out accidentally.

This change readds the feature to to capture all args after a trailing
-- and forward them down to clippy-driver via an env variable.

src/bin/cargo/commands/clippy.rs

@@ -6,6 +6,7 @@ use cargo::util;
 pub fn cli() -> App {
     subcommand("clippy-preview")
         .about("Checks a package to catch common mistakes and improve your Rust code.")
+        .arg(Arg::with_name("args").multiple(true))
         .arg_package_spec(
             "Package(s) to check",
             "Check all packages in the workspace",
@@ -69,7 +70,12 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
         .into());
     }
 
-    let wrapper = util::process(util::config::clippy_driver());
+    let mut wrapper = util::process(util::config::clippy_driver());
+
+    if let Some(clippy_args) = args.values_of("args") {
+        wrapper.args(&clippy_args.collect::<Vec<_>>());
+    }
+
     compile_opts.build_config.primary_unit_rustc = Some(wrapper);
     compile_opts.build_config.force_rebuild = true;
 

src/cargo/core/compiler/compilation.rs

@@ -79,11 +79,7 @@ impl<'cfg> Compilation<'cfg> {
     pub fn new<'a>(bcx: &BuildContext<'a, 'cfg>) -> CargoResult<Compilation<'cfg>> {
         let mut rustc = bcx.rustc.process();
 
-        let mut primary_unit_rustc_process =
-            bcx.build_config.primary_unit_rustc.clone().map(|mut r| {
-                r.arg(&bcx.rustc.path);
-                r
-            });
+        let mut primary_unit_rustc_process = bcx.build_config.primary_unit_rustc.clone();
 
         if bcx.config.extra_verbose() {
             rustc.display_env_vars();

src/cargo/ops/fix.rs

@@ -130,6 +130,9 @@ pub fn fix(ws: &Workspace<'_>, opts: &mut FixOptions<'_>) -> CargoResult<()> {
         server.configure(&mut wrapper);
     }
 
+    let rustc = opts.compile_opts.config.load_global_rustc(Some(ws))?;
+    wrapper.arg(&rustc.path);
+
     // primary crates are compiled using a cargo subprocess to do extra work of applying fixes and
     // repeating build until there are no more changes to be applied
     opts.compile_opts.build_config.primary_unit_rustc = Some(wrapper);

tests/testsuite/clippy.rs

@@ -38,3 +38,37 @@ fn clippy_force_rebuild() {
         .with_stderr_contains("[..]assert!(true)[..]")
         .run();
 }
+
+#[cargo_test]
+fn clippy_passes_args() {
+    if !clippy_is_available() {
+        return;
+    }
+
+    // This is just a random clippy lint (assertions_on_constants) that
+    // hopefully won't change much in the future.
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+            [package]
+            name = "foo"
+            version = "0.1.0"
+
+            [dependencies]
+            "#,
+        )
+        .file("src/lib.rs", "pub fn f() { assert!(true); }")
+        .build();
+
+    p.cargo("clippy-preview -Zunstable-options -v -- -Aclippy::assertions_on_constants")
+        .masquerade_as_nightly_cargo()
+        .with_stderr_does_not_contain("[..]assert!(true)[..]")
+        .run();
+
+    // Make sure it runs again.
+    p.cargo("clippy-preview -Zunstable-options -v")
+        .masquerade_as_nightly_cargo()
+        .with_stderr_contains("[..]assert!(true)[..]")
+        .run();
+}